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1. MECHANICAL TRANSMISSION
Prepared by
Md. Shaha Jalal

2. ROTARY MACHINERY
Driver Connector Driven

3. Driver
•Turbine
•Electric Motor
etc.
ROTARY MACHINERY
Connector
•Coupling
•Modifiers
Driven
•Centrifugal
•Reciprocating
•Electrical
•Others

4. Couplings
•Spring
•Rubber Tyre
•Pin and Bush
•Gear
•Universal Joint
•Rigid
•Spider
Modifiers
•Belts
•Chains
•Fluid Coupling
•Gearbox
CONNECTORS

5. WHY COUPLING????
 Couplings are used to connect two shafts end to
end in the same line to transmit torque or rotary
motion in unison at same RPM.
 Some Drives transmit power but not at same
RPM and also not with shaft in same line.
Eg: Belt, Chain,Gear and Clutch drives

6. • Compensates for angular and parallel
misalignment( Only flexible coupling )
• To restrict the axial movement of
connecting shafts.
• To reduce transmission of shock load
from one shaft to another.
PURPOSE OF COUPLING

7. BASIC TERMINOLOGY
A measure of the angle between the center lines of
driving & driven shafts, where those center lines
would intersect approximately halfway between the
shaft ends.
Angular Misalignment:

8. Parallel Misalignment:
A measure of the offset distance between the center
lines of driving and driven shafts.
BASIC TERMINOLOGY

9. Distance Between Shaft Ends (DBSE) :
Distance between the faces of driving and driven
shafts.
Driving shaft Driven Shaft
DBSE
BASIC TERMINOLOGY

10. Backlash:
Properly functioning mechanical systems need to have a
certain “clearance” (gap or play) between the components
transmitting motion under load.
Clearance is necessary to avoid interference, wear, and
excessive heat generation, ensure proper lubrication,
compensate for manufacturing tolerances, etc. Clearance
in the gear mesh means that the gap between the teeth of
one gear is by a small amount larger than the tooth width
of the mating gear. We also find a certain clearance in the
rolling bearings, namely a small clearance between the
inner race, rolling body (ball, roller) and outer race of the
bearing. The key and keyway of a shaft or hub usually
have clearance also.
BASIC TERMINOLOGY

11. Bore:
Central hole that becomes the mounting surface for
the coupling on the shaft.
Keyway:
Rectangular slot cut axially along the coupling bore.
Torsional Stiffness:
Resistance to twisting moment between driving and
driven halves of the coupling.
BASIC TERMINOLOGY

12. RIGID COUPLING
• High torque capacity
• Low Cost
• Easy Assembly
• Balancing design
•It requires same sizes of shaft
•Rigid coupling do not
accommodate for misalignment.

13. JAW COUPLING
Spider
• Large torque capacity
• Replaceable Spider
• Balancing design

14. BELLOW COUPLING
Bellow
• High torque capacity
• Balanced for high RPM
• Low Inertia
• No maintenance
• High torsional stiffness
• Constant Velocity
• Long Life
• Zero backlash

15. DISC COUPLING
Disc
• High torque capacity
• Balanced for high RPM
• Low Inertia
• No maintenance
• High torsional stiffness
• Constant Velocity
• Long Life
• Zero backlash

16. GEAR COUPLING
Transmitting higher
torques at low and high
speeds
Sleeve halves are bolted
to rigid flanges to form
two single flexing
coupling
Requires Lubrication*
*
*

17. GRID FLEX COUPLING
• Simplicity
• Lubrication
• Simple/Ease maintenance
• Low Operational Cost
• Smooth Quieter Operation

18. RUBBER BLOCK
Low Intial & Operational
Cost
Smooth Power Transmission
Compact Size*
* *
*
Effective damping of
vibrations

19. TYRE FLEX COUPLING
Accommodate angular, parallel
and axial misalignment
Protects against vibration,
Impact loads and Heavy shocks
Ease of Assembly/Disassembly.
Ease of Alignment*
*
*
*

20. Bush
PIN BUSH COUPLING
• Simplicity in construction
• Varying stiffness characteristics
• No lubrication
• Simple/Ease maintenance
• Low operational cost
• Smooth and Quieter
Operation

21. a) Type of driving and driven equipments
b) Torque characteristics:?
c) Maximum and Minimum torque:?
d) Normal and maximum rotational speeds
e) Shaft sizes
f) Span or distance b/w the shafts
COUPLING-SELECTION

22. g) Changes in span due to thermal growth, racking of
bases or axial movement of connected shafts during
operation
h) Equipment position(horizontal,vertical and inclined)
i) Ambient conditions(dry,wet,corrosive,dust etc.,)
j) Bearing locations:?
k) Cost (initial coupling price, installation, maintenance
or replacement).
COUPLING-SELECTION

23. BELT

24.  Flat Belts
 V-belts
 Synchronous Belt

25. FLAT BELT

26. • Used for general
purpose, low speed
applications.
FLAT BELT

27. A- Protective Cover
B-Tension Members
C-Cushion Compound
D-Compression Rubber
• High capacity belts are used to substantially
reduce the drive cost.
V-BELT

28. SYNCHRONOUS BELT
Also called timing belts and used when driven shaft
speed must be synchronized with the rotation of drive
shaft.

29. • Reduced vibration
• Reduced noise level
• increased power
• 100% tracking in both running directions without
flanges
• continuous tooth engagement
• Smooth interaction with idler and tensioners running
on the toothed side of the timing belt eliminating tooth
jumping, based on the overlapping tooth arrangement
SYNCHRONOUS BELT-
ADVANTAGES

30. * Has the advantage
of high flexibility of
flat belt and power
transmission rate of
V-belt.
V-RIBBED BELT

31. Belt cross
section
Load
KW
Belt top
width
(mm)
Belt
thickness
(mm)
A 0.75-5 13 8
B 2.0-15 17 11
C 7.5-75 22 14
D 22-149 32 19
BELT CLASSIFICATION

32.  Belt width in mm
 No. of Plys
 Top & Botttom Rubber cover thickness
 Belt confirming to code
 Carcase Material ..e.g. Cotton,Nylon,Rayon
 Carcase material density in OZ I.e. Weight of
carcase material per Sq yard/ply in OZ
 Rubber grade..e.g. OR/HR/SHR
HOW TO SPECIFY A BELT?

33. GEARS

34. GEAR CLASSIFICATION

35. GEAR TERMINOLOGY

36. ADVANTAGES:
•Eliminates end thrust
• Ease of assembly
• Minimum maintenance
• High strength
• Efficient
• Economical
SPUR GEAR
DISADVANTAGES:
Cannot be used when axial
direction change is required.
Can’t use for high load.

37. HELICAL GEAR
•Greater Tooth strength
•Carry more load than spur gear
•Used to mesh two non-parallel
shafts.
•Less efficient
•Expensive
ADVANTAGES:
LIMITATIONS

38. STRAIGHT BEVEL GEAR
•Transfer power between
intersecting shaft
•Limited availability
•Not used for parallel shafts
•Become noisy at high speeds.
ADVANTAGE:
LIMITATIONS

39. SPIRAL BEVEL GEAR
•Teeths are cut in curved
manner
•Smooth and Quieter
Operation
To be used for high
transmission torque.

40. WORM GEAR
•Tolerate large loads and higher
speed ratios
•Meshes are self-locking
•Low efficiency
•Higher Friction losses.
ADVANTAGE:
LIMITATIONS

41. HERRING BONE GEAR
• Side by side opposite
hand helical gears
• Eliminates thrust load
• Alignment is very critical
to ensure proper teeth
engagement.

42. CROSSED HELICAL GEAR
* Crossed gear mesh in
which two shafts are
perpendicular to each
other

43. RACK AND PINION GEAR
•Only gearing component that
converts rotational motion to
translational motion
•Highly efficient
•Limited usefulness.
ADVANTAGE:
LIMITATION

44. CHAIN
DRIVES

45. Three types of chain drives
1, Roller chains
2, Inverted tooth
3, Leaf chains
CHAIN DRIVE-TYPES

46. • Simplicity of design and selection of components.
• Relatively inexpensive
• Virtually any length of chain can be obtained by
splicing
• Bearing loads are generally lower than for belts.
• Chain drives are 95-99% efficient.
CHAIN DRIVE-ADVANTAGES

47. CHAIN DRIVE-LIMITATIONS
• Lubrication is critical- non lubricated drives can wear
300 times faster than lubricated drives.
• Lubrication attracts dirt which leads to wear problems
• Life is usually low since an estimated 90-95% of chain
drives are improperly lubricated.
• Alignment is important as it affects life and stability.
• Chain drives are noisy due to metal to metal contact.
• Jerky motion.

48. ROLLER CHAINS

49. INVERTED TOOTH
* Transmits higher torques

50. These chains are used
for lifting loads and do
not involve tooth
sprockets or gear
wheels.
They are used on fork
lift trucks an machine
tools
LEAF CHAINS

51. FLUID COUPLING

52. FLUID COUPLING

53. FLUID COUPLING-INTERNALS